Leather-like sheets such as artificial leathers exhibit softness and functionalities that are not of natural leathers, so that leather-like sheets are used for various applications such as clothing, materials.
Recently, the leather-like sheet excellent in stretch has been considered necessary particularly in use for clothing for the viewpoint of wear feeling and in use for materials for its formability.
There is a method (e.g. Patent Literature 1) for obtaining a stretchable artificial leather, in which: for example, a latent shrinkage woven fabric is formed by using a latent crimpable fiber yarn such as a false-twisted yarn or conjugate fiber made of two or more kinds of polymers with different heat-shrinkage properties as a latent shrinkage fiber; the latent shrinkage woven fabric is laminated by entanglement of ultrafine fibers; and a polymeric elastomer is applied thereto. With this method, elongation of the artificial leather depends largely on elongation of the stretchable woven fabric.
The latent crimpable fiber used as the latent shrinkage fiber means a fiber that becomes crimped by a heat treatment or a fiber that exhibits fine crimpability even before receiving the heat treatment, which is distinguished from a normal false-twisted yarn.
Specific examples may be a side-by-side type conjugate yarn made of polyethylene terephthalate (abbreviated as PET hereinafter) having difference of intrinsic viscosities or difference of limiting viscosities (e.g. Patent Literatures 2, 3), and a side-by-side type conjugate fiber made of homo-PET and copolymer PET of a more highly shrinkable (e.g. Patent Literature 4).
It is true that such latent crimpable polyester fiber yarn can exhibit stretch to a certain extent.
However, the stretch is still insufficient when it is formed into a woven fabric and when the woven fabric is laminated further into a leather-like sheet.
It is because the side-by-side type conjugate fiber described above has low crimpability when restricted within a woven fabric or because the crimp thereof is easily weaken by an external force. Unlike polyurethane fabric that utilizes stretch due to elongation of the fiber itself, the side-by-side type conjugate fiber utilizes elongation of three-dimensional coils generated by a difference of shrinkage ratios between the composite polymers. Therefore, under the restricted condition within a woven fabric or nonwoven fabric where the shrinkage of the polymer is limited, for example, it is considered that the fiber is thermally fixed with insufficient crimpability, thereby losing the higher shrinkability. This causes the above-described inconvenience.
In the meantime, there has been proposed artificial leather excellent in stretch, which is formed by entangling a woven or knitted fabric made of polytrimethylene terephthalate fiber with an ultrafine staple fiber (e.g. Patent Literature 5).
According to the information and knowledge of the inventors of the present invention, it has been found that a woven or knitted fabric made of the polytrimethylene terephthalate fiber alone is almost no elongation exhibited when made into a fabric, because the initial tensile resistance degree of the fiber made of the polytrimethylene terephthalate only is extremely high.    Patent Literature 1: Japanese examined patent application publication No. HEI 06-39747    Patent Literature 2: Japanese examined patent application publication No.SHO 44-2504    Patent Literature 3: Japanese published unexamined patent application No. HEI 04-308271    Patent Literature 4: Japanese published unexamined patent application No. HEI 05-295634    Patent Literature 5: Japanese registered patent No. 3280302